Since a processor in a multiprocessor system directly accesses a shared storage according to its physical address, data is transmitted in word units through a system bus synchronously with an access instruction. When a number of processors are provided in the system, the frequency of accesses via the system bus rises. Therefore, the number of processors in the system is limited, and therefore limits the system performance. Accordingly, a shared storage must be accessed at a high speed, and the overhead of the system bus must be reduced by minimizing its load.
A conventional multiprocessor system comprises a plurality of processor modules and a plurality of shared storage modules which are connected together by a system bus for transfer of information, thereby forming a computer system.
In such a conventional multiprocessor system, a central processing unit of each processor module is operated in a synchronous access method in which a shared storage module at its physical address space is directly accessed through a system bus according to a physical address.